obexd: Fix invalid oflag check
obexd: Fix invalid oflag check

Change logic to check for O_WRONLY, as oflag is
created by an OR operation of O_WRONLY, O_CREAT and
O_TRUNC.
Message update is a PUT function, this check returns
bad response if GET is received.

ComputeCycles/bluez,pkarasev3/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,silent-snowman/bluez,mapfau/bluez,pkarasev3/bluez,silent-snowman/bluez,ComputeCycles/bluez,pkarasev3/bluez,ComputeCycles/bluez,mapfau/bluez,silent-snowman/bluez